Self-configurable wireless local area network node

ABSTRACT

In a wireless local area network including an access controller (AC) and an access points (AP), the AC transmits a functionality inquiry to the AP. Upon receiving the inquiry, the AP transmits a query response including the functional capabilities of the AP. The AC then generates a map of the functional capabilities present in the network based on the inquiry response. Conflicting or redundant functional capabilities are identified and are disabled, enabled, or reconfigured by instructions from the AC. The AC may selectively enable and/or disable functional capabilities at nodes in the network to provide a more balanced load on the network, and to provide for load sharing by allocating functionalities between and among network nodes having common functional capabilities to satisfy a variety of situations encountered in the network.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/670,174, filed on Apr. 11, 2005, which is incorporated by referenceas if fully set forth herein.

FIELD OF INVENTION

The present invention generally relates to wireless local area networks(WLANs), and more particularly, to a method and apparatus fordetermining and analyzing network topology, configuring network nodes,and resolving functional conflicts that arise in network architectures.

BACKGROUND

The term “access point” (AP) as used herein includes, but is not limitedto, a base station, an access router (AR), a Node B, a site controller,or other interfacing device in a wireless environment that providesother stations with wireless access to a network with which the AP isassociated.

The term “station” (STA) as used herein includes, but is not limited to,a wireless transmit/receive unit (WTRU), a user equipment, a mobilestation, a fixed or mobile subscriber unit, a pager, or any other typeof device capable of operating in a wireless environment.

Typically, a WLAN includes a plurality of APs, wherein each AP iscapable of conducting concurrent wireless communications withappropriately configured STAs, as well as multiple appropriatelyconfigured APs or ARs, when configured in the “infrastructure mode”.Some STAs may alternatively be configured to conduct wirelesscommunications directly to one another, i.e., without being relayedthrough a network via an AP. This is commonly known as “peer-to-peermode” or “ad hoc mode”. Where a STA is configured to communicatedirectly with other STAs, it may also be configured to function as anAP. STAs can be configured for use in multiple networks, with bothnetwork and peer-to-peer communications capabilities.

In the infrastructure mode architecture, STAs are conventionallyconnected in a star-type topology to a central AP in order tocommunicate to each other or to connect to other external networks.Although this architecture has proven successful in the past, manyfactors, such as the increasing number of closely located APs, theincreasing number of applications for a WLAN, and the fact that APs arerestricted to public bands, have resulted in conventional infrastructuremode architectures becoming less desirable. Accordingly, otherinfrastructure mode topologies have evolved.

One topology is known as a “mesh” topology, in which WLAN nodes have twoor more paths between them which enables the nodes to communicatedirectly with each other (i.e., as in the ad hoc mode) and tocommunicate indirectly with each other (via other nodes that relayinformation). A second topology is known as a “split” architecture, inwhich one or more access routers (ARs) or access controllers (ACs) areconnected via an interconnection to APs present in the network. The ACsprovide network-wide monitoring, improve scalability, and facilitatedynamic configurability. The logical interconnection may be a directconnection to the APs, a switched connection, or a routed networkconnection. The AC and the AP may be collocated in the same physicaldevice.

In addition to exchanging configuration and control information with theAPs, the ACs “split” or share certain functionalities with the APs thatare conventionally provided solely by the APs. That is, functionstypically provided by standalone or “fat” APs are removed from these APsand are provided by the AC(s). These split-function or reduced-functionAPs are referred to as “thin” APs. This architecture is similar to aUMTS architecture, where the AC is analogous to a central radio networkcontroller (RNC) and the AP is analogous to a Node B connected to theRNC.

FIG. 1 is a diagram of a network 100 with an infrastructure modearchitecture including a plurality of STAs 102 a-102 n communicatingwith a fat AP 104. This architecture is often referred to as a fat AParchitecture because all of the medium access control (MAC) layerfunctionalities are located in the AP 104. The STAs 102 communicate withthe AP 104, and with one another via the AP 104. The AP 104 incorporatesa physical (PHY) layer 106, a real time (RT) MAC layer 108, and anon-real time (NRT) MAC layer 110.

FIG. 2 is a diagram of a network 200 with a split architecture,including a plurality of STAs 202 a-202 i, several APs 204 a-204 c, andan access controller (AC) 206. In the split network 200, certain APfunctions are split away from the APs 204 and are provided by the AC206. Although the AP functions may be split in any number ofconfigurations, FIG. 2 shows one of the most common arrangements. TheAPs 204 terminate the infrastructure side of the wireless physicallinks, provide radio-related management, and provide all RT services tothe STAs 202. The AC 206 provides the NRT management functions such asconfiguration, quality of service (QoS), access control, etc., for allof the APs 204. By sharing functionalities at a higher layer, a bettercoordinated deployment is possible.

The AP functional definitions made to support future AC-AP architecturesmust also be backward compatible to accommodate present-day devices.Since infrastructure mode networks are the present-day convention, it isnoted that accommodating hybrid architectures, i.e., those networks withboth fat APs and thin APs, will be a significant challenge for futurenetworks.

An example of a pathological hybrid network 300 with both fat APs andthin APs is shown in FIG. 3. The network 300 includes a plurality ofSTAs 302 a-302 i; two thin APs, AP1 (304 a) and AP2 (304 b); a fat AP,AP3 (306); and an AC 308. AP3 306 provides all of its L2 MACfunctionalities, including both the RT MAC 310 and the NRT MAC 312. Inthis deployment, the AC 308 manages all three APs 304 a, 304 b, 306.Accordingly, there is a conflict with redundancy in the NRTfunctionalities between the AC (NRT MAC 314) and AP3 306 (NRT MAC 312).This conflict is further aggravated in other network topologies such as,for example, mesh networks, wherein AP functionalities are distributedover the entire mesh network and wherein direct communication betweenACs and APs is not always possible.

Accordingly, it is desirable to provide a method and apparatus toresolve functional conflicts that arise in WLAN architectures.

SUMMARY

The present invention relates to a method and apparatus for configuringnetwork nodes and resolving functional conflicts or redundancies thatarise in network architectures. In a WLAN including at least one AC anda plurality of APs, the AC transmits functionality queries to the APs.Upon receiving these queries, the APs transmit query responses, whichinclude the functional capabilities of the APs. The AC then generates afunctional map of the functional capabilities available in the networkbased on the query responses. Conflicting or redundant functionalcapabilities are identified and are disabled, enabled, or reconfiguredby instructions from the AC to the APs having conflicting or redundantfunctionalities.

A method for configuring nodes in a WLAN including an AC and an APbegins with the AC sending a functionality inquiry to the AP. The APresponds to the functionality inquiry by sending its functionalcapabilities to the AC. The AC maps the functional capabilities of theAP. A determination is made whether a capability conflict exists betweenthe capabilities of the AP and the capabilities of the AC, wherein aconflict can include redundant capabilities between the AP and the AC.If there are any capability conflicts, they are resolved.

An AC for configuring nodes in a WLAN includes a transmitter/receiver,an inquiry device, a capability mapping device, and a capabilityevaluating device. The inquiry device is in communication with thetransmitter/receiver and is configured to send functionality inquirymessages to an AP in the WLAN. The capability mapping device is incommunication with the transmitter/receiver and is configured to receivefunctionality inquiry reply messages from the AP and to map thefunctionality capabilities of the AP. The capability evaluating deviceis in communication with the capability mapping device and is configuredto determine if any functionality capability conflicts exist between theAP and the AC.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description of a preferred embodiment, given by way ofexample, and to be understood in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a diagram of an infrastructure mode WLAN with a fat AP;

FIG. 2 is a diagram of a split architecture WLAN with thin APs;

FIG. 3 is a diagram of a hybrid WLAN architecture with both fat APs andthin APs;

FIGS. 4A, 4B, and 5 are flow diagrams of a method for resolvingfunctionality conflicts or redundancies between an AC and an AP in thearchitecture shown in FIG. 3; and

FIG. 6 is a block diagram of a system including an AC and an APconfigured to perform the method shown in FIGS. 4A, 4B, and 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred embodiment, a WLAN including at least one AC and at leastone AP is considered. The AC is preferably configured to split or removecertain L2 MAC functionalities (e.g., NRT MAC functions) from the AP(s)and provide these functionalities to the network. An example of thisconfiguration is shown in FIG. 3. Alternatively, the AC may provide allMAC layer functionalities to the network. As noted above, the AC maysplit and provide any functionality that is typically provided by theAPs, including MAC layer functions, PHY layer functions, securitymethods, management interfaces, etc.

The present invention is not limited to the network deploymentillustrated in FIG. 3. Rather, the present invention is applicable toany network deployment in which functional conflicts between networkcomponents occur. As previously described in connection with FIG. 3,there is a redundancy conflict with the NRT functionalities between theAC 308 and AP3 306, in that both the AC 308 and AP3 306 attempt toprovide L2 NRT-MAC functionalities, creating a problem in the network300.

Overview

Utilizing a query-response mechanism, the AC queries all associated APsregarding their respective functional capabilities. Once responses arereceived from all associated APs, the AC utilizes the responses togenerate a functional map of the different functional blocks availablein the network. This functional map enables the AC to detect whether anyAPs are providing duplicate functionalities that may cause anoperational conflict.

If an AP in the system fails to respond or is unable to respond to theAC's query, the AC may assume that the non-responding AP is capable ofimplementing all functionality modules and that a resultingfunctionality conflict exists. Failure to respond to the AC's query mayindicate one of two possible scenarios: that an AP was implementedaccording to an alternate standard or that the AP is a legacy AP notcapable of responding to the query. Since the AP will be assumed to be afat AP capable of providing all possible functionalities, the AC stopssupport of the non-responding AP.

To resolve a detected conflict or redundancy, the AC generates andtransmits a message to the AP ordering that the conflicting module inthe AP be disabled or reconfigured to resolve the redundancy. Conflictsamong network modules are preferably resolved based on the individualpriority of the modules. Modules that reside higher in the networkhierarchy (i.e., AC) are given higher priority than nodes that are lowerin the hierarchy (i.e., APs). Disabling a module in the AP preferablyoccurs after a predetermined period of time (e.g., sync-up, futureevent, etc.), at which point the AC takes control of those functions forthe AP and thus resolves the conflict.

It should be noted that the messaging means described above may also beused to enable functionalities, such as with a functionality enablingmessage. Additionally, the disabling, reconfiguring, and enabling offunctionalities may occur during a system start-up phase or dynamicallywhile the system is operating. Dynamic adjustments may be utilized, forexample, to better distribute and re-balance processing power in asystem based on functional maps and node priority. Similarly,dynamically adjusting functions may be preferred in certainarchitectures, such as mesh networks, wherein the AC functionalities arenot situated in a single network node, but are distributed acrossvarious nodes.

It is noted that an AC may split and/or provide some or all MAC layerfunctions, while allowing the APs to provide some or all PHY layer ormultiple PHY layer functions. Further, the approach described herein maybe applied to other functionalities such as to multiple PHY layers,multiple radios (RFs), multiple security methods, multiple routingalgorithms, different versions of a standard (e.g.,802.11e-WMS/WME/other), management interfaces (e.g., station managemententity (SME)), etc., wherein the AC splits and provides these functions.

AR-AP Capability Signaling

FIGS. 4A, 4B, and 5 are flow diagrams of a method 400 for resolvingfunctionality conflicts between an AC 402 and an AP 404. Although thenetwork is typically provided with a plurality of APs, only one AP 404and its interaction with the AC 402 is shown for purposes of simplicity,it being understood that the AC 402 interrogates all other APs in thenetwork in a like manner. As an initial step, the AP 404 starts up andenables all of its functionalities (step 406).

The AC 402 sends an inquiry to the AP 404 (step 410). The inquiry can besent upon initial setup or upon the entry of a new node to the network,such that the system can correctly configure itself as quickly aspossible. The inquiry can also be sent on a periodic basis (e.g., once aday as the system should not need to change too frequently) or by beingtriggered by a particular event (e.g., when a congestion conditionarises, the capabilities are gathered as a pretext for load balancing).After the inquiry is sent, the AC 402 sets a timer for receiving a replyfrom the AP 404 (step 412). The AP 404 receives the inquiry (step 414)and replies to the AC 402 providing its functional capabilities (step416).

There is a possibility that the AC 402 may send an inquiry to the AP 404(step 410) and the AP 404 fails to respond, as indicated by the dashedlines for sending the inquiry and sending the reply. Failure to respondto the AC's query may indicate that an AP was implemented according toan alternate standard or that the AP is a legacy AP not capable ofresponding to the query.

After the timer has been set (step 412), a determination is made whetherthe AC 402 has received a reply from the AP 404 (step 418). If no replyhas been received, then a check is made to determine whether the timerhas expired (step 420). If the timer has not expired, the method 400waits for a reply from the AP 404 (step 418).

If the timer has expired (step 420), this indicates that no reply wasreceived from the AP 404. The AC 402 defaults the AP 404 to having allpossible capabilities (step 422). Since the AP 404 is presumed to haveall possible capabilities (e.g., that the AP 404 is a fat AP), the AC402 also halts support of services to the AP 404 (step 424). As appliedto the scenario shown in FIG. 3, the AC 402 will not attempt to performNRT-MAC scheduling for the AP 404 because the AP 404 is presumed to havethis capability.

FIG. 4B is a flowchart of an alternate method 450 for performing theinitial steps of the method 400. The AP 404 starts up and enables all ofits functionalities (step 406). The AP 404 attempts to discover the AC402 (step 452). The AP 404 can attempt to discover the AC 402 throughvarious means. For example, the AC 402 could broadcast packetsannouncing its presence or a dedicated pre-agreed address on how to jointhe AC 402 could be known to all APs. After the AP 404 has discoveredthe AC 402, the AP 404 sends its capabilities to the AC 402 (step 454).

If the AC 402 has received a reply from the AP 404 (step 418), if the AC402 has set the AP 404 to having default capabilities (steps 422, 424),or if the AP 404 has sent its capabilities to the AC 402 (step 454), theAC 402 stores and maps the capabilities of all APs in the network (step502; FIG. 5). Next, the AC 402 determines whether the capabilities ofany AP conflict or are redundant with the capabilities of the AC 402 orwith the capabilities of another AP (step 504). The capabilities ofother APs are checked for situations where there are different levels ofAPs or where APs have different priorities within the network.

As one example, assume that the AP 404 has a plurality of functionalcapabilities, at least one of which is the same as at least one of thecapabilities of the AC 402. In order to avoid any conflict within thenetwork, the co-existence of the common function by both the AC 402 andthe AP 404 necessitates that this co-existence be resolved by preventingthe AP 404 from providing this functionality to other nodes within thenetwork. The AC 402 may utilize an associative memory technique forcomparing the AC functionalities with the AP functionalities. However,any other suitable technique for determining a conflict may be employed.

If there are any capability conflicts or redundancies (step 504), thenthe AC 402 sends a disable or reconfigure capabilities message to the AP404 (step 506). In instances where an AP may have priority over anotherAP or other APs in the network, the AP having priority is permitted tosupport the functionality in issue and lower priority APs will have thefunctionality disabled or reconfigured. In situations where none of theAPs have a higher priority level but are located at a higher level inthe network architecture hierarchy, only the AP having the highernetwork hierarchy level is instructed to continue support of thatfunctionality. In either case, the AC provides disabling orreconfiguring messages to APs at a lower network hierarchy level.

Additional factors considered by the AC include functional capabilitiesderived from cross-vendor components in which conflicts or redundanciesarise due to differences in the components or due to one of the APshaving superior operational capabilities compared with other APs in thenetwork. This situation may arise where functional capabilities areshared in common with two APs, wherein one of which is a legacy AP, andthe AC decides in favor of the more up to date module while disabling orreconfiguring the functional capability of the legacy AP.

The AP 404 receives the disable or reconfigure capabilities message(step 508) and disables or reconfigures any capabilities that conflictor are redundant with the AC's capabilities (step 510). After adjustingthe capabilities according to the message, the AP 404 sends anacknowledgement (ACK) to the AC 402 (step 512). The AC 402 receives theACK and updates the capabilities map with the current capabilities ofthe AP 404 (step 514).

The allocation of capabilities between and among the APs is not limitedto MAC layer functions and PHY layer functions and may include securitymethods, management interfaces, and the like. For example, in meshnetworks, the AC can allocate and split functional capabilities over thenetwork in order to provide better balance within the network and toalleviate potential overloading of network nodes. Alternatively,security requirements may be utilized as the overriding factor inallocating and assigning functional capabilities between and among theAPs.

If there are no conflicting capabilities or redundancies (step 504) orafter the AC 402 has received the ACK and updated the capabilities mapbased on disabled or reconfigured capabilities (step 514), adetermination is made whether any previously disabled capabilities ofthe AP 404 need to be enabled (step 516). This scenario may arise, forexample, in a load balancing situation where the AC 402 wants to enableor reconfigure functions in the AP 404 that it had previously disabledor reconfigured.

If there are any capabilities that need to be enabled or reconfigured(step 516), then the AC 402 sends an enable/reconfigure message to theAP 404 (step 518). The AP 404 receives the enable/reconfigure message(step 520) and enables or reconfigures the capabilities listed in themessage (step 522). After enabling or reconfiguring the capabilitiesaccording to the message, the AP 404 sends an ACK to the AC 402 (step524). The AC 402 receives the ACK and updates the capabilities map withthe current capabilities of the AP 404 (step 526) and the methodterminates (step 528).

If there are no capabilities that need to be enabled or reconfigured(step 516), then the method terminates (step 528).

Exemplary System

FIG. 6 is a block diagram of a system 600 including an AC 602 and an AP604 configured to perform the method 400. The AC 602 includes atransmitter/receiver 610, an antenna 612 connected to thetransmitter/receiver 610, an inquiry device 614 in communication withthe transmitter/receiver 610, a timer 616 in communication with theinquiry device 614, a capability mapping device 618 in communicationwith the transmitter/receiver 610 and the timer 616, and a capabilityevaluating device 620 in communication with the capability mappingdevice 618 and the transmitter/receiver 610.

The AP includes a transmitter/receiver 630; an antenna 632 connected tothe transmitter/receiver 630; a capability determining device 634 incommunication with the transmitter/receiver 630; a station managemententity (SME) 636 in communication with the capability determining device634, the SME 636 including a list of the capabilities of the AP 604; anda capability adjusting device 638 in communication with thetransmitter/receiver 630 and the SME 636.

In operation, the system 600 functions as follows. The inquiry device614 sends an inquiry message to the transmitter/receiver 610 fortransmission to the AP 604. When the inquiry message is sent, theinquiry device 614 sets the timer 616. The AP 604 receives the inquirymessage via its transmitter/receiver 630. The inquiry message is passedto the capability determining device 634, which accesses thecapabilities list in the SME 636 to determine the capabilities of the AP604. The capability determining device 634 then sends a reply message tothe transmitter/receiver 630 for transmission to the AC 602.

The reply message is received at the AC 602 and is passed to thecapability mapping device 618, which maps the capabilities of all APs incommunication with the AC 602. If the AC 602 does not receive a replyfrom the AP 604 and the timer 616 expires, and the capability mappingdevice 618 defaults the AP 604 to having all possible capabilities(i.e., the AP 604 will be considered to be a fat AP).

The capability evaluating device 620 examines the capability mapping forall APs and determines which APs have capabilities that conflict withthe AC 602. If there are any conflicting capabilities, the capabilityevaluating device 620 sends a disable or reconfigure message to thetransmitter/receiver 610 for transmission to the AP 604. Upon receipt ofthe disable or reconfigure message by the AP 604, it is forwarded to thecapability adjusting device 638 which disables or reconfigures thecapabilities specified by the message by signaling the SME 636 whichupdates the capabilities list accordingly. Once the capabilities aredisabled or reconfigured, the capability adjusting device 638 sends anACK to the AC 602.

In a similar manner, if the AC 602 instructs the AP 604 to enable orreconfigure any capabilities, the capability adjusting device 638enables or reconfigures the capabilities specified by the AC 602 bysignaling the SME 636 which updates the capabilities list accordingly.Once the capabilities are enabled or reconfigured, the capabilityadjusting device 638 sends an ACK to the AC 602.

Although the features and elements of the present invention aredescribed in the preferred embodiments in particular combinations, eachfeature or element can be used alone without the other features andelements of the preferred embodiments or in various combinations with orwithout other features and elements of the present invention. Althoughthe various embodiments discussed above are described with reference tocertain layers, it should be understood that any of the embodiments canbe implemented in any layer or any combination of layers. Further, thefeatures and elements of the present invention may be implemented on asingle integrated circuit, such as an application specific integratedcircuit (ASIC), multiple ICs, discrete components, or a combination ofdiscrete components and ICs. Moreover, the present invention may beimplemented in any type of wireless communication system.

1. A method implemented in an access controller (AC) for configuringnodes in a wireless local area network, comprising: transmitting afunctionality inquiry; receiving a response to the functionalityinquiry, the response including functional capabilities of an accesspoint (AP), wherein the functional capabilities include media accesscontrol layer functionalities; mapping the functional capabilities ofthe AP as if the AP had all possible functional capabilities on acondition that a response to the functional inquiry is not receivedafter a predetermined time; determining whether a capability conflictexists between the functional capabilities of the AP and the functionalcapabilities of the AC, wherein a conflict can include redundantcapabilities between the AP and the AC; and resolving the capabilityconflict.
 2. The method according to claim 1, further comprising:storing the functional capabilities of the AP.
 3. The method accordingto claim 1 further comprising: transmitting a capabilities disablemessage.
 4. The method according to claim 3, further comprising:receiving an acknowledgement, wherein the acknowledgement indicates thatthe AP has successfully disabled the conflicting capabilities.
 5. Themethod according to claim 1 further comprising: transmitting acapabilities reconfiguration message.
 6. The method according to claim5, further comprising: receiving an acknowledgement, wherein theacknowledgement indicates that the AP has successfully reconfigured theconflicting capabilities.
 7. The method according to claim 1, furthercomprising: setting a timer in response to the functionality inquirybeing transmitted; determining that the timer has expired; and mappingthe functional capabilities of the AP as if the AP had all possiblecapabilities, the mapping being performed after the timer expires. 8.The method according to claim 1, further comprising: halting support ofservices to the AP on a condition that no functional inquiry response isreceived after the predetermined time.
 9. An access controller (AC) forconfiguring nodes in a wireless local area network, comprising: atransceiver; an inquiry device configured to transmit functionalcapability inquiry messages to an access point (AP) in the network,wherein the functional capabilities include media access control layerfunctionalities; a capability mapping device configured to receivefunctional capability inquiry response messages from the AP and to mapthe functional capabilities of the AP; a capability evaluating deviceconfigured to determine whether a functional capability conflict existsbetween the AP and the AC; and a timer configured to: start in responseto the inquiry device transmitting the functional capability inquirymessage; and alert the capability mapping device in response to thetimer expiring.
 10. The AC according to claim 9, wherein the capabilityevaluating device is further configured to transmit functionalcapability disabling or reconfiguring messages.
 11. The AC according toclaim 9, wherein the capability mapping device is configured todetermine whether the response message has been received and on acondition that no response message has been received, the capabilitymapping device is further configured to map the functional capabilitiesof the AP as if the AP had all possible capabilities.